Sealing floor of older aquaplate watertank

[Bags]

I have an older aquaplate watertank that is now out of warranty. When I cleaned it out I discovered one floor panel has lots of bubbles erupting (looks like rust erupting) and there seems to be some damage to the polymer coating. The rest of the floor and the walls all look fine. What would be the best way to repair and seal this damage? I've attached a couple of photos.

[SilentButDeadly]

Give the bubbly bits a bit of a rub with a wire brush then a dab of Cold Gal or Galmet then repaint the entire floor with Bondall Aquatite www.bondall.com.au (http://www.bondall.com.au)

[Bags]

Thanks Silent,
I have researched the Bondall website. The Aquatite looks good, but the data sheet stated that it wasn't rated for 'potable water tanks'. I rang their helpline and the suggestion was the water-based bitumen lining which the tech-guy said should be painted on the whole inside of the tank...not just the base. I wasn't keen on painting the inside with black bitumen, but he said the product had been tested to be used with drinking water. It also takes 7-10 days to cure, which is a pain for me if I miss out on any rain. I wonder if there are any other suitable products out there?

[malb]

Bags, I would also be a bit coy about bitumen paint, as the information pamphlet that came with our aquaplate tank specifically warns about not introducing petroleum based materials because they affect the coatings.

Concreters left me a very rough surface on tank pad and I don't dare slide my tank (22550l) accross the slab to position it as it will scrape the outer base coating off. Thought of covering slab with Melthoid and bit paint till I read the non petroleum warning. Will now be topping the slab with ceramic tile underlay sheets bonded on, and a metal safe silican gap sealer.

The top coating looks reasable in the pics. Is it possible to lay the empty tank over and check that the problem hasn't started underneath and wormed it's way through. I would be cautious about a scratch and patch approach until I knew where the problem started from.

[Bags]

Thanks for the advice Malb. I am trying to get a Bluescope technical rep to come and inspect the problem. I'll let you know what he says about bitumen products if he comes. I personally would like to find an alternative treatment/sealant...don't like the thought of drinking water sitting on bitumen. Our local tank manufacturer recommends putting malfoil under aquaplate tanks.

[Fog_Watch]

malfoil
Hi,

What's Malfoil?

My problem is similar. I have a new aquaplate tank that needs a couple of patches to repair some damage that was sustained during transport. I would also like some rust protection 100mm up the sides. I was thinking bituminous paint, but the tip here is no. Hmm, I might end up using that Aquatite goop. I wonder if it sticks to the PVC of the floor.

Regards

Fog_Watch.

[Barry_White]

I would be putting pressure on the Bluescope rep to replace the bottom of the tank.

Although the tank bottom should have double sided aquaplate on it to prevent corrosion from the outside. If it hasn't it's a cop out from the tankmaker suggesting putting the malfoil under it. It depends on what the tank was sitting on also.

BTW roof and gutter silicone is the sealant of choice on aquaplate.

[Fog_Watch]

Hello Bazza

I don't think I was clear. The aquaplate of the bottom has a PVC coating facing down, as you would expect. It's just that the PVC was perforated during transit. It is those couple of perforations that need patching.

The water proofing up the sides is because I expect the tank to be sunk 100mm or so into the soil below surface. Ergo, I'm a bit worried about soil eventually banking up against the side a rapidly corroding the gal finish.

Regards

Fog_Watch.

[Barry_White]

Fog_Watch

I was mainly replying to Bags' post but silicone would seal the damaged area on the base of your tank. I would certainly be concerned about burying a gal tank although a bitumen coating would not effect the gal coating but I would be a bit concerned about the aquaplate surface with the bitumen.

I think the only tanks that should be buried are concrete ones

[Bags]

To me it seems the bubbling/rusting problem has been caused by little chunks of metal embeded into the polymer lining. Don't know how they got there - possibly someone grinding nearby the sheet in the tank factory or possibly from metal chunks left on the floor after manufacture. As the metal rusted it caused the polymer lining to bubble and started rusting the galv sheet below. Not covered by the warranty. I'm going to treat it by cutting off the tops of the bubbles, remove any corrosion (scrape back to bare metal), maybe treat any rust holes into the galv sheeting with a dab of cold galv, then cover with some 780 plumbing and roof sealant. Its going to take me ages! One tip for everyone interested: when you get a new metal tank, get in and sweep up any loose metal fragments before adding water to prevent them rusting and adhering to the floor.